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The new lichen species Gyalideopsis mexicana is described from Chihuahua, Mexico. It is characterized by a crustose, badly delimited thallus, branched diahyphae carried by erect hyphophores, and submuriform spores; it grows on mosses and plant debris. The species is known from five localities in the Sierra Madre Occidental. The lichen genus Gyalideopsis was firstly introduced by VWzda (1972) to accomodate four species with transversely septate to densely muriform spores, and with a continuous, loose network of anastomosing paraphysoids immersed in a gelatinous matrix forming both the proper margin of apothecia and the hamathecium. Many species of this genus have vegetative diaspores carried by hyphophores, which are specialized structures functionally analogous to synnemata. V~zda (1972) placed Gyalideopsis in the lichen family Asterothyriaceae R. Sant., sharing several characters in common with Tricharia Fre and Calenia Muill. Arg., but subsequently V~zda and Poelt (1987) assigned it to Gomphillaceae Hafellner; this interpretation has been accepted by subsequent authors. A large number of new species of Gyalideopsis have recently been described, mainly from the Tropics (Kalb & V~zda 1987, 1994; Kantvilas & Vizda 1992; VWzda & Hafellner 1988, 1991), but also from temperate Europe (James 1975; Puntillo & VWzda 1992; V~zda & Poelt 1973). To date, the genus contains about 50 species. In the summer of 1994, two of the authors (M.G. & M.T.) took part to an international excursion to Mexico organized by Thomas H. Nash, III, Arizona State University, in the framework of the Sonoran Desert Lichen Flora Project. During this excursion some areas of the Sierra Madre Occidental were visited that had never been explored by lichenologists. In several localities, abundant material of a crustose lichen with erect, stipitate hyphophores that occurred on mosses and plant debris was collected; fertile material was found at only a single locality. This lichen proved to be a new species of Gyalideopsis and a formal description is given in this paper. GYALIDEOPSIS MEXICANA Tretiach, Giralt, & Vrzda sp. nova (FIG. 1-5) Thallus tenuis, crustaceus, plantas destructas emortuas praesertim muscos incolens, verruculis albidis circ. 0.20.5 mm latis formatus, hyphophoris copiosis instructus; hyphophori stipitati, 1.0-1.8 mm alti, apicibus globosis vel conicis usque 0.2 mm diam.; stipes cylindricus, hyalinus, basim versum 100 pxm, ad apice attenuatus et circa 50 pm crassus; pars apicalis globosa vel conica, pallide fusca, subpellucida, diahyphis copiosis in fasciculum singulum, circa 150 pm longis, 1.5 pm crassis, ad septa haud constrictis composita. Apothecia orbicularia, 1.5-2.0 mm lata, 0.2-0.4 alta, basim versus constricta, interdum subs ipitata, discis concavis vel planis, badiis, marginibus paulum elevatis, integris, pallide fuscis. Excipulum 100 pxm crassum, hyalinum, badium superficiem versus, ab haathecio haud distincte limitatum; hypothecium pallide fuscum, KOH immutatum. Hymenium 70-100 pIm altum, z na epihymeniali fusca, ceterum hyalinum. Paraphyses ramosae anastomosantesque luminibus 1 pxm crassis. Asci 2-8 spori. Ascosporae ellipsoideae, (16-)20-26(-28) x (8-)9-12(-14) jim, submurales vel murales, septis transversalibus (2-)3-4(-7), longitudinalibus 1-3. TYPE: MEXICO. CHIHUAHUA. Sierra Madre Occidental, Rio Sirupa Valley, 29010'55"N, 108018'45"W, on decaying mosses, ca 1,700 m, 20 July 1994, Tretiach (holotype, TSB 20033; isotype, MEXU); ibid., Giralt (paratype, BCC 9201). Further isotypes will be distributed in V6zda, Lichenes Rariores Exsiccati). Thallus mainly in small orbicular patches, crustose, thin, badly delimited, verrucose, whitish glaucous to pale gray when dry, vivid green when wet, growing on decaying mosses or on plant debris, more rarely directly on soil, warts whitish, + 0.20.5 mm in diam. Hyphophores always present, usually abundant, crowded, erect, stipitate, 1.0-1.8 mm high; stalk translucent, ca 100 pLm in diam. at base, 50 pCm at apex, when immature with pointed apex; conidial mass (sensu S6rusiaux & de Sloover 1986) apical, white or pale brown, translucent, globose or conic, up to 0.2 mm in diam. Diahyphae numerous, branched, +150 pLm long, 1.5 pIm thick, septate 0007-2745/96/236-239$0.00/0 This content downloaded from 207.46.13.101 on Sat, 08 Oct 2016 06:10:13 UTC All use subject to http://about.jstor.org/terms 1996] TRETIACH ET AL.: GYALIDEOPSIS MEXICANA 237

Caloplaca wetmorei is described as new from southern Baja California, Mexico. The new species, with a lobulate-laciniate, pseudoisidiate thallus, grows parasitically on several epilithic lichens, and is characterized by spores without septum or, exceptionally, with a very thin, continuous septum, recalling those of some species of Fulgensia. Besides the type collection the species is also known from the state of Sonora (Mexico) and from Colorado and Arizona (U.S.A.). During the Sonoran Desert Excursion, 7-25 February 1993, organized by Prof. T. H. Nash III, the Sierra de la Laguna, in southern Baja California, was investigated for the first time by lichenologists. The top of this range (2,400 m) hosts a mixed Quercus-Pinus forest with many endemic phanerogams. On large granitic boulders a very peculiar Caloplaca was collected, growing parasitically on different crustose epilithic lichens. It is characterized by a small, marginally lobate thallus with erect, fingerlike lobules simulating isidia; the spores are simple, or, more rarely, have a very thin, continuous septum, which is quite untypical for Caloplaca species. From a screening of the taxonomic literature concerning North and Central America this lichen seemed to be still undescribed. We sent a specimen to Dr. C. Wetmore, who is monographing Caloplaca in North America, who confirmed that the species seems to be new. Our lichen is very well characterized by three important features: pseudoisidiate thallus, spores with thin continuous septum, and parasitic growth, and its description as a new species seems to be justified.